Diesel fuel



Patented Dec. 8, 1942 DIESEL FUEL Gould 11. Cloud, Elizabeth, N.J.,assigno1 to Standard 011 Development Company, a corporation ofDelaware No Drawing. Application March 22, 1939, Serial No. 253,407

6 Claims.

This invention relates to a stabilization of compression-ignition enginefuels and is concerned particularly with improved fuel compositionsadapted for high speed engines of the Diesel type by addition compoundswhich enhance ignition qualities of the fuel.

In most instances, addition compounds which have been recommendedforaccelerating ignition of hydrocarbon oils in Diesel engines .havecharacten'stically contained oxygen, nitrogen, and

sulfur, in highly unstable groupings. While it is true that many ofthese proposed compounds are very efiective in shortening thedelayperiod between injection and spontaneous ignition of the fuel,particularly when the fuel isfreshly made up, a reduction in theireifectiveness tends to occur during storage owing to their inherentinstability. Not only do these unstable compounds tend to deteriorate,but on deteriorating they tend to induce oxidation of hydrocarbons inthe fuel which results in gum formation and further, they tend todevelop corrosive decomposition products in storage and in operation ofthe engines.

The objectof this invention is to provide an improved Diesel fuelcomposition with a novel stabilizing agent, which, added to the fuel byitself or in combination with unstable types of ignition promoters, hasa definite and substantial beneficial influence on the ignition qualityof the fuel.

Compounds suitable for use as stabilizing promoters according to: thepresent invention are certain organic nitrogen compoundscharacterized'by having adequate solubility in hydrocarbon oil andchemical properties which adapt them for inhibiting oxidation andcorrosion. Compounds responding to these requirements were I found to benotably hydrazines, certain hydrazine derivatives, andcertainrelated'nitrogen bases. These compounds behave exceptionally wellin enhancing the qualities of Diesel fuel oils, since, in general, thepresence of an amino or an imino group in a compound has appeared tocounteract ignition-promoting action generally, for example, aromaticamines, e. g aniline, and their usual derivatives, including azo andhydrazo compounds, have been determined to be detrimental to theignition qualities of a fuel.

Hydrazines which are used in the-practice of this invention belong .to awell known class of unsymmetrical compounds identified by the presenceof nitrogen in the groupings NH-NH2,/

-hhNH; and NH-NH--. Members of this class of compounds found to bepreferably useful are dimethyl hydrazine, phenyl hydrazine, diphenylhydrazine, and methyl. phenyl hydrazinein each'instance, the methyl andphenyl groups being replaceable by higher homologous hydrocarbonradicals. Similarly suitably hydrazine rderivatives and related nitrogenbases are quin- 'alyl hydrazine, acetyl phenyl hydrazine, 3-amino phthalhydrazine, carbazole, 5-amino uracil, and

tribenzyl amine.

The manner of employing the compounds which possess desirable propertiesfor promoting qualities and stability in Diesel fuels and of testingtheir eflicacy in these respects is illustrated in the followingdescription. A number of samples were prepared by dis solving from lessthan 1% to about 3% by vol--. gl5 ume of the compound to be tested in aportion of a 40 cetane number gas oil, and each sample was tested in ahigh speed Diesel engine according to the method disclosed in the S. A.E. Journal of June, 1936, page 225. Each sample was rated on its cetanenumber by comparison with blends consisting of cetane and alpha meth-.yl naphthalene. Since the ignition lag of a blend consisting of normalcetane and alpha-methyl naphthalene is shortened very nearly in propor-25. tion to the increase in percentage of cetane by volume, the ignitionquality of a fuel can be evaluated in terms of the cetane content ofsuch I a blend giving comparable performance in the test engine. i

Even though a number of aliphatic amines,

aromatic amines, and their derivatives consistently showed an adverseeifect on the cetane number of the fuel samples, the dialkyl, diaryl,and alkyl-aryl hydra/zines and hydrazine derivatives, particularly thoseenumerated, made a substantial improvementin ,the cetane number ofthefuel. The compounds selected as preferable are those which increasethe cetane number of a fuel on the order of 2 or more points whenincorporated in concentrations of less than about 1% by volume of thefuel. Further tests on fuel samples blended with mixed ignitionpromoters show that by-usingthe compounds capable of promoting andstabilizing ignition qualities of the fuel together with additioncompounds having higher potency for accelerating ignition but lackingstability, the ignition qualities of the blended fuel is increased atleast in proportion to the 50. effect of each promoter. Considerableimportance is attached to this fact, because ignition I promoters areclostly in comparison to the value of hydrocarbon fuels, making lthighlydesirable to eliminate any detrimental influence of promoters withoutimpairing their ignition accelerating action.

To prepare the Diesel fueLcompositions which can be stored for longperiods without detriment to the ignition qualities, also with reducedacid and sludge formation, the ignition promoting- 2 stabilizingcompound need be used only in less than about 1%, whether used alone ortogether with .5% to about 5% of addition compounds such as aromaticperoxides, aliphatic nitrates, aliphatic nitrites, aliphaticpolysulfides, and the like. About .2% to 1% of the stabilizing promoteris generally adequate, but with more readily oxidizable fuels or moreunstable addition compounds as much as 3% may be used.

Every hydrocarbonv oil suitable as a fuel for Diesel engines may beimproved in the described manner. Ordinarily, the hydrocarbon fuel to beused may be said to have a boiling range above that of gasoline, and,more particularly, the boiling range and viscosity of hydrocarbonspresent in a gas oil which boils from 400 F. to 700 F.

Under some circumstances, a more narrowly cut fraction such as onedistilling from about 400 F.

' or 450 F. to 800 F. may be used. Considerable for enhancing variousother qualities without detracting substantially from the ignitionqualities of the fuel may be admixed, such as oiliness agents, dyes,pour point depressants, and viscosity modifiers.

Practical advantages obtained in using'the stabillsing promoters are:

1. Economy in the use of more potent ignition promoters which aresubject to degradation when used without a stabilizing agent:-

2. Protection of storage tanks and engine parts from corrosivedecomposition products of the more potent ignition promotersr 3.Stabilization of the fuel against the aeve tpment of insoluble gums andresins which tend to clog fuel lines and atomizers; and r 4. Eliminationof substances having harmful and annoying physiological effects fromexhaust gases.

The above description and examples are to be taken as illustrative onlyand not as limiting the scope of the invention. Any modification orvariation therefrom which conforms to the spirit of the invention isintended to be included within the scope of the claims. I

I claim:

1. A compression-ignition engine fuel comprising a hydrocarbon oilboiling from 400 F, to 700 F. and as an ignition improver andstabilizing agent a minor amount of anessentially hydrocarbonunsymmetrically substituted hydrazine com pound selected from the groupconsisting of dialkyl hydrazines, phenyl hydrazine,' diaryl hydrazines,alkylaryl hydrazines, quinalyl hydrazine, acetyl phenyl hydrazine,3-amino phthal hydrazine 2. A fuel composition described in claim 1having admixed therewith a minor amount-of an ignition acceleratingagent selected from the class consisting of aliphatic" nitrates,aliphatic nitrites, aromatic peroxides, and aliphatic polysulfldes.

3. A compression-ignition engine fuel comprising a hydrocarbon Dieselfuel oil and as an igni- .tion improver and stabilizing agent a minoramount of an unsymmetrical hydrazine containing a hydrocarbonsubstituent radical.

4. A compression-ignition engine fuel comprisin a hydrocarbon Dieselfuel oil and .2.% to 1% of phenylhydrazine.

5. A compression-ignition engine fuel compris- 8' a hydrocarbon Dieselfuel oil and 2% to'1.% of methyl phenyl hydrazine.

6. A compression-ignition engine fuel comprising a hydrocarbonDieselfuel oil and .2% to 1% of an unsymmetrical essentially hydrocarbondiaryl hydrazine.

\ GOULD H. CLOUD.

